Tests show that the six people found dead at a luxury hotel in Thailand's capital Bangkok died from cyanide poisoning, according to the Thai police. The police have found traces of the poison in cups and thermoses in the room.
The bodies were discovered early on Tuesday morning by a cleaner. One of the dead is also believed to be the person behind the poisonings. According to recordings from surveillance cameras and hotel documents, there were no other visitors in the room, which was locked from the inside.
Thailand's Prime Minister Srettha Thavisin visited the site in the evening, where a large media gathering had assembled.
The dead have been identified as two American citizens of Vietnamese origin and four Vietnamese citizens aged 37 to 56.
A poisoned couple among the deceased had invested money together with two of the other victims to build a hospital in Japan. The police suspect that a financial settlement may be behind the deaths. According to the police, it is unlikely that it is a case of mass suicide, since some of the victims had planned for further travel in the country and had hired guides and drivers.